Electrostatic bonding apparatus



Baily 13 19430 E, L. @RANIDELL ELECTROSTATIC BONDING APPARATUS Filed June 18, 1941 I 220822302 Ea um L. 02 M, y

flfifoa zzgy WJUM Patented July 13, 1943 2,324,068 ELECTROSTATIC BONDING APPARATUS Ervin L. Crandell, Wellesley, Mass, assignor to Compo Shoe Machinery Corporation, Boston, Mass., a corporation of Delaware Application June 18. 1941, Serial No. 398,630

2 Claims.

This invention relates to bonding apparatus and relates more particularly to bonding apparatus utilizing high frequency electrostatic fields for generating heat in materials such as plastics for softening same for bonding, and for generating heat in adhesives for cementing plies of material such as leather, together.

This invention provides a roller type press for bonding layers of material together, the bonding being accomplished by heat and pressure.

A feature of the invention resides in utilizing the pressure exerting rollers in a roller type press, as electrodes for the production of the electrostatic fields for heating.

Another feature of the invention resides in providing in the roller type press, an electric switch for opening the circuit supplying high frequency energy to the electrodes when a worl: surface has passed through the press.

An object of the invention is to utilize high frequency electric energy in a roller type press for the generation of heat in materials to be bonded. v

The invention will now be described with refer= ence to the drawing, of which:

Fig. 1 is an end elevation of a roller type press embodying this invention;

and

Fig. 3 is a diagrammatic view of a suitable high frequency electric source for supplying energy to the electrodes of the press.

The base 5 of the press has mounted thereon the four upright supports t. The metal bars l are attached to the lower ends of the supports ii, and have journalled therein the bearings 8 which support the cylindrical, metal roller 9.

lhe oars it of electric insulating material are slidably positioned along the supports 6. The springs i l have their upper ends attached by the clamps it? to the upper ends of the supports 6 and are attached at their lower ends to the insulating bars it, and serve to support the bars ill on the supports 6 while at the same time, they bias the bars ill towards the lower bars l.

The bearings iii of the cylindrical, metal roller i i are journalled in the bar it. The springs ll thus act to force the rollers 8 and it together for exerting pressure on the work to be bonded as will be described.

The lower roller 9 is rotated through the pulley l8 and belt is by the pulley of the electric motor 2i and acts to move the work piece 22 therethrough.

Fig. 2 is a side elevation of the press of Fig. i,

The work piece 22 illustrated comprises two plies of leather with an adhesive therebetween.

The roller i l is connected through its bearing 63 and shaft it: to the electric conductor 36 which is connected to the ungrounded side of a suitable high frequency electric oscillator.

The metal oar l is connected by the electric conductor ii to the grounded side of the oscilletor and serves to connect the roller 9 thereto. The electric switch 23 is mounted on one end of one of the bars 7 and has the upwardly extending actuating plunger 26. The screw 25 is threaded through the bar to in alignment with plunger and its lower end is adjusted so that when the work piece 22 is between the rollers, it just clears the plunger 23, and when the work piece has cleared the rollers, the movement or" the roller it towards the roller El by the springs ii, causes the lower end of the screw to depress the plunger 2d of the switch 23 causing to open the circuit from the high voltage direct current source to the anode 26 of the oscillator tube El, this discontinuing the supply of electric energy to the rollers 9 and i The oscillator circuit is a conventional one, the vacuum tube triode 2? having one end of the tanlr coil connected through the blocking con denser 29 to its anode 26 and having its other end connected to the cathode 39 of the tube and to ground. The anode 26 is connected through the radio irequency choke 3!! to a high voltage direct current source. The conductors it and ii to the rollers it and 9 respectively, are connected to opposite ends of the tank coil and receive high frequency electric energy which may have a frequency for example, of 20 megacycles, therefrom. i

In operation, the rollers El and i i act as electrodes and establish a high frequency electrostatic field therebetween which heats the adhesive between the piles of the work strip 22 as eX- plained in the Pitman' Patent No. 2,087,480 for cementing the plies together. The rollers also press the plies of the work strip together for causing them to adhere.

Thermoplastic plies may be bonded together without the necessity for an adhesive therebetween, the plastic becoming softened under the influence of the heat as is well known. Heat is generated in plastics, adhesives and other substances having dielectric properties as explained in said Pitman patent and the plies referred to in the appended claims are plies, layers or strips of materials having such dielectric properties or are plies of other material having adhesives having such dielectric properties interposed therebetween.

The invention has been found useful for cementing plies of leather together as in laminating outsole blanks with a skiving in order to thicken same.

While one embodiment of the invention has been described for the purpose of illustration, it should beunderstood that the invention is not limited'to the exact apparatus and arrangement of apparatus illustrated, as modifications thereof may be suggested by those skilled in the art without departure from the essence of the invention.

What is claimed is:

1. Apparatus for bonding plies, comprising opposed rollers having metai plie contacting surfaces for exerting pressure upon the plies; resilient means urging said rollers towards each other; means for electrically insulating said rollers from each other; means forming a high frequency electric source; means connecting said rollers as electrodes to said source for the production of an electrostatic field therebetween, and means including one of said rollers for advancing plies to be bonded between said electrodes.

2. Apparatus for bonding plies, comprising means including opposed rollers having metal plie contacting surfaces for exerting pressure upon the plies; resilient means urging said rollers towards each other; means forming a high frequency electric source; means insulating said rollers electrically from each other; means including said rollers forming electrodes connected to said source for providing an electrostatic field therebetween; means including one of said rollers for advancing plies to be bonded between said electrodes, and means including means actuated by movement of said rollers close together by removal of said plies, for discontinuing the supply of energy from said source to said electrodes.

ERVIN L. CRANDELL. 

